Blackboard.



PATENTED AUG. 18, 1903.

No. 736,431. V A. E. A. OPITZ.

BL-AGKBOARD. APPLICATION FILED MAR. 19. 1903.

3 SHEETS-SHEET 1.

H0 MODEL.

110 MODELv maa 13),. 71:" n

7 A. E. A; OPITZ BLACKBOARD. APRLIO'ATION FILED MAB.

PATENTED AUG. 18, 1903.

3 SHEETS-SHEET 2.

PIATENTBD AUG. 18/1903.

- A. E. A. OPITZ.

BLAGKBOARD.

APPLICATION FILED MAR. 19, 1903.

Mums-Bunnia.

N0 MODEL.

iatented August-18, 190's.

PATENT OFFICE. Y

ARNOLD ERNST AUGUST OPITZ OF OLDESLOE, GERMANY.

,BLACKBOARD.

SIECIFIQATION forming part of Letters Patent No. 736,431, dated August 18, 1903. 1 Application filed MarchlQ, 1903. Serial No. 148,531. (No model.)

To all whom it may concern.-

Beit known that I, ARNOLD ERNST AUGUST OPITZ, a citizen of the German Empire, and a resident, of .Oldesloe, Holstein, Germany, have invented certain new and useful Improvements in Blackboards, of which the following is a specification.

This invention embraces a blackboard which can be adjusted and fixed at any desired angle and adjusted vertically in slotted arms or secured so as to permit of horizontal adjustment by means of a string or cord actin g on two arms resting against the wall from which the board is supported. A board so constructed is illustrated in the accompanying drawings, in which.

Figure 1 is a front elevation, and Figs. 2, 3, and 4 are side elevations, of the board in three diiferent positions. Fig. 5 illustrates the fixing device in elevation; and Fig. 6 shows the same in cross-section on line A B, Fig. 5, on a larger scale.

On a horizontal batten 1, secured to the wall, are mounted brackets 2, to which two arms 3 are pivoted by means of pins 4. The arms 3 carry at about fifty centimeters from their upper ends a spindle 5, to the ends of which are secured arms 6, resting on metal plates 7, let into or secured to the wall. These arms are held against the wall or the plates 7 by means of the weight of the arm 8, secured to one of the arms'6.= To the arm 8 is also attached a chain, string, or the like 9, by the aid of which the arms 3, carrying the board 10, are forced away from the. wall. Centrally on the spindle 5 is a pulley 12 in a block 11, and to the latter is secured a string, cord, or the like 13, passing first over a pulley 15 in a block 16, attached to the board 10 by a string, chain, or the like 14, and then only over the pulley 12, rotatable on the spindle 5. By this means the board 10 may be raised or lowered. The string 14 is attached to the block 16 of the pulley 15.

To the wall are secured two battens 17, fitted with inclined projecting ribs 18, against which the board 10 rests.

The arms 3 are providedat their lower ends with slots 19 about fifty centimetersin length, and with these engage bolts 20, projecting from the board 10 and provided with a collar 21, against which the arm 3 is forced by a thumbnut 22, Fig. 6. Behind the collar 21 the bolt is also screw-threaded and has mounted thereon a hand-wheel 23, which when revolved forces the toothed inner end 24 of the bolt 20 into corresponding notches or teeth of a nut 25, which at the same time affords support to the bolt 20 and is let in into the board 10. The hand-wheel 23 rests the wheel 23 is rotated, so as to bring it against the collar 21 of the bolt 20, the board 10 can be turned, the teeth of the bolt-head 24 having been brought out of engagement with the teeth of the nut.

For the purpose of obtaining an additional security against accidental turning in case of heavy boards a ring 27 is secured at one end of the board around the bolt 20 to the nut 25. This ring is provided with a series of holes 28 to receive a locking-pin 29, attached by a small chain 30 to the arm 3 and introduced through the slot 19 of the arm 3, thus insuring perfect fixing even of heavy boards.

When the board 10 is to be used in a hori zontal position, Fig. 3, it is secured in re cesses 31 of the ribs 18, so that it can be used as a table and carry a considerable weight.

In Fig. 2 the board 10 is shown resting on the ribs 18.

In Fig. 4 the board 10 is shown reversed and in an inclined position, and from this it will be seen that the string 14 need not be detached when it is desired to turn the board 10, so as to use the other side. The pulley 15 comes behind the board 10 when the string 13 is released, as may be seen in Fig. 4.

What I claim is-- v g 1. The combination of a pair of pivoted slotted arms, with a connecting-shaft, means for inclining the arms, a blackboard adjustably suspended from the shaft, and bolts on the blackboard that engage the arm-slots, substantially as specified.

2. The combination of a pair of pivoted slotted arms, with a connecting-shaft, braces on said shaft for inclining the arms, ablackboard adjustably suspended from the shaft, and bolts on the blackboard that engage the arm-slots, substantially as specified.

3. The combination of a pair of pivotedslotted arms,with a connecting-shaft, a blackboard suspended therefrom, notched nuts secured to the blackboard, toothed bolts engaging said nuts and the arm-slots, a perforated ring mounted upon one of the bolts, and a pin engaging said ring, substantially as specified.

ARNOLD ERNST AUGUST OPITZ.

Witnesses:

1. Tours, E. H. L. MUMMENHOFF. 

